Low power wireless networks such as sensor networks, PAN (personal access network), BAN (body area network), etc., have received an increasing interest for industrial automation, personalized entertainment and personal healthcare. Typically the devices in these networks are small in size and are required to conserve their battery life. Therefore, it is needed that they operate at low power though with a relatively low symbol rates. The choice of efficient transmission and reception protocols which trade-off energy with symbol rate become an important aspect in the design of low power wireless networks.
The form of signal processing algorithms employed at the receiver is very critical to the design of energy-efficient transmission protocols. It is well-known that receivers are broadly classified into coherent and non-coherent receivers. A coherent receiver makes use of the phase information in demodulation of symbols, whereas a non-coherent receiver is mainly based on envelope detection with no phase information. Typically, coherent receivers yield better performance than the non-coherent receivers at the cost of power and complexity. Due to the capability of exploiting the phase information, coherent communication supports bi-polar modulation alphabets whereas non-coherent communication supports unipolar alphabets. Thus, typically, a communication network is designed so as to exclusively support either coherent or non-coherent receivers. However, many communication networks which involve low power constraints might be required to support both coherent and non-coherent receptions. This stems from the fact that some receivers employ non-coherent reception due to the system processing and power constraints. Therefore, in such networks, transmission scheme needs to be designed to ensure that it is suitable for both types of receivers. Further, in many cases, due to practicability, transmitter is assumed to be agnostic of the type of the target receiver, thereby making the design task more challenging.